Biochemical analysis of total collagen content and collagen types I, III, IV, V and VI in gingiva of various periodontitis categories.

Collagen is one of the chief components of the extracellular matrix of gingival connective tissue, where five different types have been identified to date. The molecular mechanism of collagen loss in periodontitis still needs to be explored. In the present study total collagen content was investigated in gingival connective tissue of adult periodontitis (AP) as well as early onset periodontitis patients (EOP) and clinically healthy subjects. Furthermore, collagen type I, III, IV, V andVI content was evaluated in gingival biopsies obtained from periodontitis patients. There was a statistically significant difference between AP (25.1 +/- 8.1 microg/mg) and EOP (15.6 +/- 4.0microg/mg) groups with regard to the total collagen content (P < 0.05). In the clinically healthy control group the total collagen content was 20.7 +/- 4.6microg/mg. Moreover, the distribution of collagen types exhibited variations in pooled homogenates of each periodontitis group. The total collagen loss seemed to be greater in the EOP patients than in the AP patients. When the ratio of fibril forming collagens to nonfibrillar collagens was evaluated, it seems to be decreased in AP patients in comparison to EOP patients. The findings of the present study suggest that different collagen types present in various periodontitis categories may be related with diverse pathogenic mechanisms acting in these diseases.